[Tim Simmons]

Drawing wire has been a venerable craft in central and southern Africa for hundreds of years. It is believed that this was mostly drawing copper wire. Brass is know and examples have been found in southern Africa but again it is believed that the widespread use of brass is after European imports or more importantly the native manufacture of brass could not compete with European imports. A book "Red Gold of Africa, Copper in Precolonial History and Culture" University of Wisconsin press, is a good introduction and basic over view of non ferrous metal in Africa. So it is quite possibly that your examples could well come from earlier in the 19th century.